um, they work via 2.5Ghz transmission.. I own a few of those too, but promptly swapped them out for IP Cameras.
I found the cameras themselves are the limiting factor... I removed one of the cameras and hooked the transmitter up to a good quality sony handicam...
Night and Day difference..
ok, to the how to...
you need some form of Video In. Hook the camera reciever to that, and your good to go.